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Thread: CYA value higher AFTER draining 2/3 of pool

  1. Back To Top    #1

    Join Date
    Nov 2018
    Newnan, GA

    CYA value higher AFTER draining 2/3 of pool


    We are hoping someone can shed a light on an issue we have with our CYA.

    Oct 1 - Water tested by local pool store CYA = 128

    Nov 15 - Water tested by our local pool maintenance company using their Taylor test kit = CYA too high to get a value

    Nov 15 - Water tested by local pool store CYA = 136

    Last week we drained 2/3 of the pool --- about 22,000 gallons. We refilled the pool with local tap water. Nothing else has been added. The pool company says the CYA using their Taylor test kit is too high to get a value.

    My husband and I purchased a Taylor kit 2005C. We tested the CYA and it looks over 150.

    How can the CYA be higher after draining 2/3 of the pool?

    The local pool company wants us to completely drain the pool this week 33,000 gallons and pay for them to acid wash it. Bye the way calcium hardness is fine and there are no stains in the pool. The pool was built in 2004 but the pebbletec finish is very nice.

    Has anyone else had this situation?

    Kind regards,

    Stephanie in Newnan GA
    Pool 34K gal. IG Pebbletech, 1.65 HP 230V Super Pump VS700 Omni VS Pump, Pentair Quad 80 DE Filter 160 GPM, Hayward CL200 In Line Chlorine Feed, Multiport Valve Kit, Freeze Guard, Dolphin S300I - Salt planned spring 2019 // SPA 1500G IG Pebbletech, Pebbletech, 1 HP Sta Rite Pump, Sta Rite Cartridge Filter, Hayward CL200 In Line Chlorine Feed, 400K BTU Hayward H Series Heater, Freeze Guard, Other: City water, Ordered Taylor K-2006 kit.

  2. Back To Top    #2
    Mod Squad Texas Splash's Avatar
    Join Date
    Jun 2014
    South-Central Texas, Marion/San Antonio

    Re: CYA value higher AFTER draining 2/3 of pool

    Hi Stephanie. Simply put - probably poor testing before. Since there is no stabilizer in local water, CYA will not increase unless you add it - either directly or as a byproduct in items like bags of shock and/or chlorine tablets (pucks). Your sig shows the inline chlorinator. Are you keeping that stocked full? If so, that's part of the problem. As for the pool store tests, you can just about ignore them all. Pool store CYA tests are horrible and almost never produce an accurate CYA test. It's good you ordered your own K-2006 test kit (according to your sig). Use that once it arrives and base your water exchanges (if any) on those results.
    CYA Testing:
    Proper lighting is critical for the CYA test, so you want to test for CYA outside on a bright sunny day. Use the mixing bottle to gently mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, then gently mix again. Recommend standing outside with your back to the sun and the view tube in the shade of your body at waist level. Then, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. To help the eyes and prevent staring at the dot, some people find it better to pour & view in stages. Pour some solution into the viewing tube, look away, then look back again for the dot. Repeat as necessary until you feel the dot is gone. After the first CYA test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, gently shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate your own CYA reading. Finally, if you still doubt your own reading, have a friend do the test with you and compare results.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  3. Back To Top    #3

    Join Date
    May 2018
    Clovis, CA

    Re: CYA value higher AFTER draining 2/3 of pool

    Easy -- pool store results were horribly inaccurate, as would be expected from a pool store. They are often inaccurate at high CYA levels (err... at all CYA levels).

    The pool maintenance company should have been able to perform the test using the dilution method. There is no excuse for them to not know about that, other than they don't know what they are doing. In your case probably mix 1 part pool water with 3 parts tap water, then multiply CYA result by 4.

    Acid wash? Is there a reason why? CYA is not one.

    See what you get with your own kit, then consider a new pool company, or even better, learn the TFP method, because if you want it done right, you do it yourself.
    15,000 gal. gunite in-ground; Pebble Tec / Pebble Fina in Bella Blue; Waterway OASIS pool controller; Waterway Power Defender 1.65 VS Pump; Waterway 570-0425 cartridge filter; Pentair 140 Heat/Cool Pump; Pentair Rebel pool cleaner; 3x Globrite color LEDs; 3x 36 in. sheer waterfalls
    Built April 2018; TF-100 Test Kit with Speedstir - Build

  4. Back To Top    #4
    aussieta's Avatar
    Join Date
    Jan 2014
    Langwarrin, Victoria, Australia

    Re: CYA value higher AFTER draining 2/3 of pool

    if you took the sample back without draining the water the poolstore would have still gotten a different answer
    you got what you paid for
    SWG inground peanut shaped eco-bright concrete pool
    50,000 litres 13,000 gallons
    Lincoln Salt Chlorinator, 25 gram cell Sand Filter with glass media
    Taylor K2006-C test kit, Taylor K-1766 salt test, Dolphin M500 pool cleaner
    are you taking care of your pool or is the poolshop taking care of you

  5. Back To Top    #5

    TFP Guide
    ajw22's Avatar
    Join Date
    Jul 2013
    Northern NJ

    Re: CYA value higher AFTER draining 2/3 of pool

    Step 8 at Pool School - CYA tells you how to get accurate CYA levels when CYA is over 90.
    IG 20x50 35,000 gal Cayman Lagoon Hydrazoo plaster w/ spa & waterfall, Pentair Intellichlor SWG, Pentair Mastertemp 400BTU Nat Gas Heater, Pentair FNS Plus 60 DE Filter, Polaris 380 cleaner, Meyco solid winter cover, TF100 Test Kit, Built in 2000 & replastered in 2017

  6. Back To Top    #6
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: CYA value higher AFTER draining 2/3 of pool

    You got two good readings that would explain what happened.
    Water tested by our local pool maintenance company using their Taylor test kit = CYA too high to get a value
    It's not uncommon for CYA to be 400 or higher in a tablet fed pool, so draining 2/3rds of it would still mean that it's over 100 and possibly as high as 200.

    I don't see any reason to completely drain it and have it acid washed.

    I'd say just drain another 1/2 and see where that gets you to.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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